Why do they burn gas constantly in oil refineries?
In: Engineering
Oil is a mix of different hydrocarbons. Basically, a chain of carbon with oxygen and hydrogen attached to it. Gasoline is one length, bitumen is another, diesel, etc.
Refineries work by basically boiling the oil. Each type of hydrocarbon has different boiling points so they can use this to refine the oil into specific types.
This process results in the useful products and some that are useless. The gas they burn at the top of the towers are basically the hydrocarbons that are too short to be useful (or otherwise not worthwhile to recover) and they need to burn it for safety/environmental reasons.
Two main reasons:
1 – a pilot light is always burning so that if they ever need to release a lot a gas quickly due to an emergency like a pressure build up, the gas ignites and burns off.
2 – some flammable byproducts of the refining process are toxic and bad to have build up but will gladly burn into less toxic things, so they burn them as they are being made.
In addition to what others have said, some burning is sudden and unplanned. The refining process is like a huge moving train. You can’t halt the whole thing suddenly. If there’s a problem downstream, you have a bunch of products upstream that need to go SOMEWHERE. If it can’t go downstairs bc of a problem downstream sometimes the best option is to burn them off.
It’s worth noting that some of that gases produced during refining are themselves massive greenhouse gases and thus simply burning them and producing Carbon Dioxide is actually *an improvement* in terms of environmental damage.
I work for an Air Quality regulatory agency in an oil and gas state, so this is something that we deal with all the time. This practice is called flaring, and it is used primarily to reduce emissions of harmful gasses, especially methane and volatile organic compounds (VOCs). Methane has a very high global warming potential, much higher than CO2. So, instead of venting the methane directly to the atmosphere, it is burned in a flare, and the products of the combustion reaction (CO, CO2, NOX) are then emitted. These products are considered less damaging to human health and the environment than uncombusted hydrocarbons, so flaring is preferred to venting. That said, there is a current regulatory push to reduce routine flaring and encourage the capture and usage of those vapors instead (see NSPS OOOOa, OOOOb, and OOOOc).
You mean flaring? It is actually a flare to improve safety and make the process of making chemicals more efficient and safe. You see some product produce byproduct and leftovers are sometimes better to undergo a chemical reaction under high temperature and oxygen (burning) than to leave in the process, tubes and tanks.
There are also “scrubbers” that help filter what’s being flared to reduce more of the “less good” stuff.
There can be emergencies (hopefully and thankfully kept to an absolute minimum) where flaring regardless of how bad is still far better than a failure in the refinery. These incidents and exceedances are carefully monitored and require substantial reporting to regulatory authorities.
Also, burning byproducts produces heat which generates a plume to carry the final (combustion outcome) byproducts up into the higher atmosphere for wider dispersal away from humans and other animals.
They let the gas out so it doesn’t explode from the depressed pressure. Plus they burn it to control the gas from spreading (can be toxic).
ELI5: Imagine we have a big balloon filled very bad air but the other half of it is filled with delusiocs jucie. If poke it with a big straw the balloon goes boom!! lets make two holes with small straws and make bad air go bye bye with fire so we have awsome air and sipp our juice all day long yay!!
Because they don’t have the infrastructure (pipeline capacity) to capture and market it – and it would be worse to just release it into the atmosphere.
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